JPH069255A - Powdered animal protein foaming agent, method for producing the same and use thereof - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a powdery protein foaming agent suitable for producing a foam such as cellular concrete, a method for producing the same, and an application thereof. [Structure] Among keratin proteins, feather is used as a raw material, and a reducing agent and a side reaction inhibitor are hydrolyzed in combination with alkalis to obtain an aqueous solution of polypeptide having a molecular weight of 1000 to 2000, which is powdered by spray drying or the like. An animal protein foaming agent. [Effect] Since the foaming agent is a powder, there is no odor of conventional keratin protein foaming agents, and when used in concrete, lightweight concrete having excellent heat resistance and water resistance can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foaming agent containing keratin protein as a raw material, which has a low utility value as a raw material, and is made of feathers of birds such as chickens which may cause waste pollution. A foaming agent having foaming properties, stability, odorlessness, and workability superior to collagen protein foaming agents, a method for producing the same, and various excellent concretes produced by using the powdery foaming agent Regarding the product.

[0002]

It is already known to use hydrolyzed proteins as foaming agents. Conventionally, collagen protein of animal skin, tendon, bone, etc. was used as a raw material, and this was hydrolyzed with alkali to produce a peptide-like foaming agent, but these raw materials are useful as edible protein. For this reason, there are many raw materials that are not cheap and are impure so that the raw materials must be purified. Therefore, problems such as cleaning and drainage occur, and the living environment, location, and economy are greatly restricted. In addition, these proteins are relatively expensive as raw materials, and have a peculiar malodor when the product decomposes collagen protein, and there is a feeling of resistance during use, and a concrete product manufactured using this has a malodor. There were remaining drawbacks. In addition, a keratin protein foaming agent made from cow's hoofs and horns is also used, but it is not easy to decompose, so it is difficult to obtain peptides with a narrow molecular weight distribution, and the growth and history of animals are constant. Because it is not, it is difficult to obtain a certain quality because the decomposition degree of raw materials varies.
This tendency was remarkable because the keratin protein belongs to the hard protein and is not easily decomposed.

A conventional foaming agent composed of a collagen protein and a keratin protein is 40
It was supplied as a 50% to 50% strength aqueous solution. For this reason, the progress of time-dependent hydrolysis of the protein, the deterioration of the product stability due to putrefaction, and the lowering of the foaming power have occurred.
Furthermore, since a stabilizer for obtaining the stability of bubbles is dissolved, this causes a chemical reaction with the protein to form an insoluble precipitate, resulting in a markedly unstable quality. Furthermore, it is difficult to obtain an odorless foam because a bad odor is generated due to the hydrolysis after the product is made.

[0004]

INDUSTRIAL APPLICABILITY The present invention is useful as a raw material from feathers, which will be a problem of waste disposal in the future, because it is by-produced in large quantities in a bird processing factory such as an edible chicken processing factory and has little utility. Further, the present invention provides a powdery protein foaming agent having a foaming power superior to that of a conventional foaming agent, and using the foaming agent, it is odorless and comprises independent bubbles having a fine and uniform bubble diameter. The purpose is to provide concrete products and the like.

The conventional protein foaming agent is an aqueous solution having a concentration of 40% to 50%, and there are many problems in storage due to aging and also problems in transportation, whereas the present invention provides a final product. It was possible to solve these problems by drying and pulverizing the powder, or by directly spraying it into a powder form. In particular, the spray-dried powdery product is a porous body and is excellent in solubility and foamability and gives the most preferable result.

[0006] In addition, since the conventional protein foaming agent requires raw materials for animals such as cows and horses, it lacks long-term supply stability and changes in the raw material components and the degree of cross-linking due to the growth history of the animals. Applications are limited due to different degree of decomposition and odor. In addition, it is difficult to obtain a certain product because the quality of the foamed concrete products manufactured using these conventional foaming agents is unstable, and the air bubbles are uneven, and a bad odor remains in the finished product. There was a flaw. The powdery protein foaming agent according to the present invention is formed into an aqueous solution immediately before use, and since a mixture of an aqueous solution of a foaming agent and an aqueous solution of a stabilizer is used, constant bubbles are always obtained, and a mixing ratio with concrete is also obtained. A stable and stable foam concrete product can be obtained. Furthermore, since the foaming agent is almost odorless, the finished concrete product can be almost odorless.

[0007]

The protein foaming agent of the present invention is obtained by decomposing a keratin protein into a polypeptide having a molecular weight of 1000 to 2000, and in particular, a feather has a molecular weight of 10
It is composed of a protein hydrolyzate hydrolyzed to a polypeptide of 00 to 2000.

The keratin protein has a disulfide bond (-S
-S-) has a reticulated bond, which makes it difficult to decompose, and it is difficult to obtain a certain quality of raw material. The present invention has been completed by focusing on the fact that the composition is almost constant, and therefore the composition quality of the feathers is constant and the growing years are young, so that decomposition is easy.

In the present invention, as the keratin protein raw material, it is possible to use a feather meal processed for feed as a raw material, but it is advantageous to directly use bird feathers as a raw material from the viewpoint of cost. Feathers from the edible chicken processing plant are clean enough to be used as they are and can be used as they are.
With a water content of 70% to 70%, it produces 1000 tons or more per month, and can be used sufficiently as a raw material. In particular, the feathers from the edible chicken processing plant keep the edible chicken to a certain quality, so the breeding chickens are of the same breed and it is uneconomical to grow meat for an unnecessarily long period. Therefore, after being bred for a certain period of time, the meat is processed at once, so the growth rate is the same. Therefore, the content of the raw material protein, the constituent amino acids of the protein, and the degree of cross-linking are the same, and the decomposition treatment and the like can be easily carried out and decomposed to the same molecular weight.

As a result of further research by the present inventor, in order to use a keratin protein as a foaming agent, a molecular weight of 1000 to 20
It was found that a good foaming effect can be obtained by using a polypeptide of 00. Here, the molecular weight means an average molecular weight. The molecular weight may be measured by an ordinary method, for example, a sedimentation equilibrium method by ultracentrifugation, or simply a viscosity measurement method. In the present invention, the molecular weight of the polypeptide of 1000 or less is film strength, because the film forming ability is low, it is not preferable in terms of foaming power, and the stability of the foam, the molecular weight of 2000 or more is inferior in foamability. Was empirically recognized.

As described above, in the case of the protein raw material of the conventional foaming agent, for example, when animal hide is used, most of them have hair on the surface of the animal skin, and therefore the protein of hair and that of the skin are different, so that they are decomposed. The molecular weight and protein constituent molecules of the obtained polypeptides were different, and the foaming power was uneven. Further, when the growth period is long, the degree of the network structure due to cystine bonds and disulfide bonds (-SS-) in the keratin protein is large, and the degree of degradation tends to be uneven, and it is difficult to obtain a certain polypeptide.

Since the present invention uses feathers from a edible chicken processing plant with a constant growth rate, it can be easily hydrolyzed and a good foaming agent having the above-mentioned molecular weight distribution can be obtained. In addition to the keratin protein, the feathers also contain some other proteins, and in the case of the present invention, it is considered that these proteins also contribute to the foaming power in some way. Various kinds of feathers such as chicken and duck can be considered as the raw material,
From the viewpoint of the supply of raw materials and the consistency of quality, it is preferable that they are from the egg production plant or the edible chicken factory, and the feathers of chickens raised within one year, such as broilers, are good.

The method for producing the protein foaming agent of the present invention will be specifically described with reference to FIG. In the present invention, the raw material feathers are decomposed by putting the well-washed feathers continuously coming out of the chicken processing plant into the decomposition vessel. In the raw material feather treatment step of FIG. 1, a surfactant such as sodium dodecylbenzene sulfonate (sodium dodecyl benzene sulfonate ( DBS) is added. The amount of the surfactant is slightly different depending on the kind, but in the case of DBS, it is added to the feathers in an amount of about 1% in powder form. Then add an appropriate amount of water. About 5 times the amount of water is added to the weight of dry feathers.

Next, the feathers placed in the reaction kettle are hydrolyzed. The hydrolysis is carried out by adding an alkali decomposing solution. Specifically, an appropriate amount of caustic soda, slaked lime, or other alkaline agent is used for the raw material feathers, mercaptoethanol for breaking the cystine bond, thioglycolic acid are added, and sodium bisulfite, sodium sulfide, etc. are further added. It is advisable to add a reducing agent and a side reaction inhibitor. These chemicals are dissolved in water and added as an aqueous solution.

In the case of keratin protein degradation, extremely stable lanthionine produced by a secondary reaction of thiol group, vinyl group, aldehyde group and the like produced when the cystine bond is cleaved significantly inhibits alkaline degradation. There is a theory. As a result of research, the present inventor has found that
It has been found that alkali decomposition is rapidly performed when hydroxyl groups, piperazine and methylamines are added as complex reaction inhibitors (side reaction inhibitors) to inactivate the aldehyde group and thiol group. The amount of chemicals used is empirically determined to be a fixed amount. From the viewpoint of workability, economy, and stability of quality, it is preferable that the decomposition is carried out at 100 ° C. to 120 ° C. for about 1 hour in a pressure vessel. After completion of the decomposition, the hydrolyzed liquid in the filtration step is filtered to separate the decomposed liquid and the residue. Since the residue contains a large amount of organic substances, it can be used as a fertilizer, for example. Next, neutralize the decomposition solution with phosphoric acid etc.
Adjust the pH to 7.0 and stop the decomposition reaction.

The proteolytic solution used as a foaming agent is
It is desirable that the protein be decomposed into a polypeptide having a molecular weight of about 1000 to 2000. Therefore, as the alkali used for hydrolysis, it was found that good results can be obtained by using limes, which have a slower action than caustic soda. Also,
When the liquid is neutralized at the end of decomposition, caustic soda has a large amount of salt remaining in the foaming agent, but when using limes, most of the insoluble salt is neutralized with phosphoric acid or oxalic acid. Since it becomes a precipitate, it is easily removed in the filtration step after neutralization. In addition, the insoluble salt formed at this time coprecipitates with impurities in the decomposition liquid, and therefore has an advantage of clarifying the filtrate. Since calcium phosphate is obtained as the filtration residue in the step when phosphoric acid is used as the neutralizing agent,
Can be used as fertilizer.

The filtrate obtained in the above filtration step is 40-50%
Since it can be obtained at the following concentrations, add a bubble stabilizer as needed and concentrate to a concentrated solution of 50% or more. Concentration may be carried out by heating to evaporate water or a vacuum concentration method,
If desired, a freeze-drying method or the like can also be used. As the bubble stabilizer, a conventionally known one can be used. When the surfactant is used as the foam stabilizer, an anionic surfactant such as DBS is used. The amount used is 2-3% based on 50% decomposition concentrate
It is good to add some.

The conventional foaming agent is used as a foaming agent by adding aluminum salt, chromium salt, iron salt, aldehydes, etc. to the proteolytic solution obtained in the above steps as a foam film stabilizer. Although it is commercially available, according to the research of the present inventor, since these stabilizers have strong reactivity with proteins, when they are contained in a foaming agent solution, various insolubilization reactions occur during storage, resulting in insolubility. It has been found that there is a drawback that precipitates a solidified product and makes the quality unstable. Therefore, in the present invention, the decomposition concentrate obtained above is used as it is, or the decomposition concentrate containing the anionic surfactant is dried and powdered. Since the product of the present invention is used by mixing the aqueous solution of the powdered foaming agent and the aqueous solution of the stabilizer immediately before use, the above-mentioned drawbacks of the conventional foaming agents can be completely overcome. Further, it has been found that a surfactant can be used as a foam enhancing agent and a stabilizer. As described above, an anionic surfactant can be used as the above-mentioned surfactant, and cationic and nonionic surfactants are not preferable.

The decomposition concentrate obtained is filtered if necessary and then dried. Drying is preferably carried out by directly applying a spray drier to obtain a dry powder, but in addition to this, the concentrated liquid is poured into a disk or a drying drum to be dried to obtain a flake, which is optionally pulverized to a powder. The particle size of the obtained dry powder varies depending on the concentration of the hydrolyzed solution and the size of water droplets during spraying, but it is preferable that the size of the obtained powder falls within a particle size distribution of 40 to 50 microns. When the spray method is used, the obtained powder becomes a porous body, so that the solubility is good and the workability is improved.
When it is made into flakes, the volume is about three times as large as that of the powder obtained by the spray method, but the solubility is similarly good.

The spray-drying of the hydrolyzed solution is usually carried out by spraying the hydrolyzed solution in a hot air stream to the extent that the protein is not oxidized in the air. However, when the protein has a large molecular weight, it is oxidatively decomposed during the drying. The molecular weight may be adjusted. Spray drying may be performed in a non-oxidizing gas such as nitrogen gas or carbon dioxide gas, if necessary. Since a conventional foaming agent has a stabilizer added thereto, when it is made into powder, a chemical reaction proceeds during heating and drying, and the foaming agent becomes completely insoluble and cannot be used. In the case of the present invention, such a phenomenon does not occur at all since the foaming agent main body and the conventional stabilizer are separately provided for use. When a surfactant is used as a stabilizer, the above reaction does not occur during heat drying.

According to the present invention, ammonia, hydrogen sulfide, which is generated in the decomposition process of protein and dissolved in the decomposition liquid,
Malodorous gas components such as mercaptan are scattered and removed by the drying and powdering process of the decomposed solution by a spray dryer, etc., so that the obtained product is almost odorless and various applications can be developed. For example, conventional keratin protein-based foaming agents have been used in aerated concrete and foam extinguisher used in parts where odor is not a problem because the above malodor remains in the product, but the foaming agent of the present invention is almost Since it does not emit an odor, in addition to the conventional applications, it is possible to add perfumes and fragrances to make artificial wood and the like from aerated concrete. The bubbles obtained by the aqueous solution of the foaming agent of the present invention are stronger than the conventional ones and show a bubble state for a long time. For reference, the strength of the foamed film of various protein foaming agents and surfactants is shown in FIG.
Shown in. As can be seen from the figure, the keratin protein shows strong foam film strength at a low concentration.

[0022]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto. Example 1 1 kg of chicken wings from an edible chicken factory were sampled in a pressure cooker, 10 L (liter) of water was added, and a surfactant (DBS) was added in order to emulsify the oil / fat in the wings and improve the penetration of chemicals. Add 1% to feathers and stir well. Then slaked lime
100 g, sodium bisulfite 10 g and hydrazine 10
Add g and decompose at 100-120 ℃ for 1 hour. After completion of the decomposition, separate the decomposition residue and the supernatant, and add phosphoric acid to pH 7.0-
Neutralize to 7.5. The neutralized solution is filtered to remove the calcium phosphate generated, and the filtrate is spray dried to form a powder. A powdered foaming agent is obtained in an amount of about 40% by weight, based on the weight of the dry bird feathers.

Example 2 400 g of dried feathers and 2000 cc of water were placed in a pressure kettle, 20 g of a surfactant was added, and the mixture was well stirred. Next, add 100 g of slaked lime, 5 g of sodium sulfide and 10 g of methylamine, and add 100 ° C.
Decomposes at ~ 120 ° C for 1 hour. After completion of the decomposition, the decomposition residue and the supernatant are separated and then neutralized to pH 7.0-7.5 with phosphoric acid.
The neutralized solution is filtered to remove calcium phosphate, and the filtrate is spray dried to give a powder. 150 g of dry powder product are obtained.

Example 3 Portland cement 5000 g Sand 5000 g Water 2000 cc The above mixture was put in a kneading mixer and kneaded thoroughly for 2 to 3 minutes. A foam liquid prepared by foaming a foaming agent liquid is added to the cement mixture thus obtained. Powder foaming agent 40 g Water 1000 cc Foaming stabilizer 2 g The above foaming agent mixture is stirred and dissolved, and this is put into a foaming machine and well foamed for 1 to 2 minutes. Mix the completely foamed liquid, which is an aggregate of bubbles with a size of 20 to 30 μm (micron), into the above mixture of cement and sand, knead it well for 2 to 3 minutes, and then mix it into a mold. Set the pouring. The hardened cement thus set was covered with a foamed polyurethane sheet containing water according to a conventional method and cured for about 1 week to give a completely hardened product. The obtained cement hardened product was lightweight concrete in which fine air bubbles were uniformly dispersed and contained. After that, this cement hardened product was left to dry in a well-ventilated shade and dried, as described below.
It did not break even when heated to the extent that it glows red with the flame of the gas burner. On the other hand, the cement hardened material similarly hardened using the conventional commercially available liquid keratin protein foaming agent was easily damaged by the heating of the burner. In addition, a lightweight concrete plate having a thickness of 30 mm was prepared from the above composition, a glass tube was erected on this plate surface, and water was put into it to meet JIS A 5403 6.5.
When the test of (water permeability test of asbestos slate) was conducted, it was confirmed that the water permeability was 3 mm or less, that it was completely waterproof and that the bubbles were independent bubbles. In the above, the powder foaming agent used was that obtained in Example 1.

Example 4 Portland cement 5000 g Sand 5000 g Water 2500 cc The above mixture was put in a kneading mixer and well kneaded for 2 to 3 minutes to obtain a mixture having a volume of about 6000 cc and a specific gravity of 2.1. The cement mixture thus obtained was mixed with the aerated liquid obtained by the method of Example 3 in the following amount and cured to obtain aerated lightweight concrete, and its specific gravity was measured.

[Table 1] The specific gravity of the concrete shown in Table 1 above almost agrees with the calculated value, and it is recognized that the obtained lightweight concrete does not have a volume decrease upon curing, which is usually called "thinning".

Example 4 A mixture of the cement mixture of Example 3 and 2000 cc of air bubble liquid was placed in a plastic bat having a volume of 1000 cc, and the bat wall and the solidified concrete body were allowed to stand for 24 hours and then set. The boundary surface was observed, but it was confirmed that there was no clearance and the volume did not decrease.

Example 5 Portland cement 2500 g Sand 2500 g Gravel 2500 g Water 1500 cc A cement plate mixed with the above was mixed with 4000 cc of an air bubble liquid to prepare a concrete plate having a thickness of 10 cm and a specific gravity of 1.4 in the same manner as in Example 3. Cut this after solidification. When the cross section was examined, it was found that the sand and gravel were uniformly dispersed.

Example 6 When the bubble mixture was mixed with the cement mixture of Example 3, a cement-bubble mixture was prepared by mixing a fragrance of a cypress scent into the bubble mixture, and the mixture was hardened into a wood to form a pseudo-wood. When it was created, a conventional wood-like concrete material with no bad odor was obtained.

[0029]

EFFECTS OF THE INVENTION When comparing the conventional foaming agent mainly composed of animal protein with the foaming agent of the present invention made from the feather keratin protein of the bird, the keratin proteolysis of the present invention is as follows. It can be seen that the foaming agent is superior. 1. The conventional keratin proteolytic foaming agent has a peculiar malodor of cystine-derived mercaptan, hydrogen sulfide, ammonia, etc. and has a resistance to work, and the malodor remains in the foamed concrete. The keratin protein-decomposing foaming agent from a bird's feather of the present invention has a low growth rate of the raw material feathers and is easy to decompose, so the occurrence rate of the malodorous gas body is low, and the decomposed solution is spray-dried. Since it is dried, the malodorous gas is scattered and a product that is almost odorless can be obtained.

2. Conventionally, it takes 5 to 6 hours to decompose the hooves and horns of cattle and horses, which have been used as raw materials for keratin protein foaming agents, but bird feather keratin protein is easily decomposed and made into a solution, and 1 hour is sufficient. Therefore, it is very advantageous in terms of workability and fuel cost. Further, in the case of the hooves and horns of cattle and horses, they cannot be used as they are as raw materials and must be crushed in advance, which requires expense and labor, but in the case of feathers, there is no such problem.

3. When making an aerated concrete product using a keratin protein foaming agent, the conventional foaming agent causes a malodor to remain in the concrete product, and the quality of the foaming agent is not stable, so that a uniform and constant product can be obtained. Can not. When the foaming agent of the present invention is used, the resulting concrete product is almost odorless, and the foaming agent is used as a powder separately from the foaming stabilizer, and the quality is always constant because it is blended immediately before use. A foam is obtained. Therefore, it is possible to always obtain a constant aerated concrete. Since air bubbles are stable and fine air bubbles of uniform size are evenly distributed in the concrete product, it is possible to produce aerated concrete having excellent soundproofing, moistureproofing, and heat resistance.

4. The conventional keratin protein-decomposing foaming agent made from cow's hoof and the foaming agent according to the present invention were compared in terms of foamability and foam stability by a simple test method, and excellent results were shown. The results are shown below.

Test Method 0.6 cc of the foaming agent stock solution was diluted to 20 cc with water, placed in a 200 cc graduated cylinder, covered and vigorously shaken up and down 10 times to create a bubble. The measurement, expressed in (cm ³ ) number, was carried out immediately after foaming, 1 hour later,
It went after 10 hours. The stock solution of the present invention is a 40% aqueous solution of the powdered foaming agent obtained in Example 1 above, and 10 g of aluminum sulfate is added to this solution as a stock solution. An aluminum sulfate prepared in the same manner as in Example 1 except that it was hydrolyzed with caustic soda for 5 hours was used.

[0034]

[Table 2]

As can be seen from the results in Table 1 above, the foaming agent of the present invention maintains the foaming state for a long time. Further, since the foamability is also good, it is possible to obtain a foamed state by simple stirring. Therefore, it can be used not only for the production of conventional foamed concrete and foam extinguisher, but also for various foaming applications. The foaming agent of the present invention may be stored and supplied in the form of powder and liquefied at the time of use, so storage costs, transportation costs, etc. are not required, and stabilizers such as preservatives are added unlike conventional water-soluble agents. Since it is not necessary, it has many excellent advantages such that it can be used without impairing the original foaming power of the foaming agent. The foaming agent of the present invention in powder form can be stored for a long period of time by putting a desiccant or an oxygen absorbent in a plastic container, a metal can, etc. and sealing it, and used as an aqueous solution. At that time, the foaming power was no different from that at the time of manufacturing.

In the independent foaming concrete body produced in Example 3, the distribution of foaming was uniform at each site, and the sand of the aggregate was also dispersed without separation. The conventional foamed concrete using a foaming agent has a weak air bubble coating strength, so the aggregate sand tends to separate, the foaming distribution is uneven, and the foaming sizes are not uniform, so that the quality is constant. There wasn't.
Therefore, since the aerated concrete body produced in Example 3 has a constant quality, it exhibits particularly excellent heat resistance, moisture resistance, and soundproofing. As an example, take the foamed concrete body with a thickness of about 5 cm, place the shaft of the matchstick on it, heat from the bottom with a direct flame of gas, and heat red until the heated surface reaches 800-1000 ° C However, the axis of the matchstick remained as it was. In addition, the foamed concrete body that glowed red maintained its original shape like a ceramic without collapsing or deforming after cooling. Conventional cellular concrete body is 500 ~ 6
It usually cracks and breaks at around 00 ° C. Therefore, using the powdered protein foaming agent of the present invention in the production of an aerated concrete body or an aerated concrete construction method using a conventional foaming agent, immediately before use, the foaming agent and the stabilizer are mixed as an aqueous solution and foamed. It is considered that if the method of making an aerated concrete body is performed, a great improvement can be obtained in various aspects that have been performed so far. The various uses and application aspects are listed below.

(1) Tunnel backfilling injection (2) Shielding work injection (3) Filling of cavities created by falling rock, ground subsidence, etc. (4) Backwall injection for reinforcing walls and masonry (5) Levee Filling voids in the concrete back surface (6) Various injection work (7) Insulation and back-injection into the heat insulating surface (8) Lightweight panel for housing (9) Simulated wood and other simulated products (10) Other lightweight concrete products in general, ( 11) Fireproof structural panels and fireproof structures for field driving, such as walls, ceilings, roofs, floors, etc. (12) Manufacture of foamed mortar moldings and foamed plaster products.

[Detailed Description of Drawings]

FIG. 1 is a flow sheet showing a method for producing a foaming agent of the present invention.

FIG. 2 is a graph showing the foam film strength of various foaming agents.

Claims (5)

[Claims] 1. An animal protein foaming agent comprising a protein hydrolyzate obtained by decomposing a keratin protein into a polypeptide having a molecular weight of 1000 to 2000 and drying it into powder. 2. The animal protein foaming agent according to claim 1, wherein a polypeptide having a molecular weight of 1000 to 2000 obtained by alkaline hydrolysis of feathers is dried into a powder form. 3. Among keratin proteins, feathers are used as a raw material, and a reducing agent and a complex reaction inhibitor are used in combination with alkalis,
Hydrolyzes to 1000-2000 molecular weight polypeptide,
A method for producing a protein foaming agent, which comprises drying this in powder form. 4. A concrete product produced by using the powdery animal protein foaming agent according to claim 1 or 2. 5. The method for using the powdery animal protein foaming agent according to claim 1, which comprises mixing an aqueous solution of a foaming agent with a stabilizer immediately before use.